1. Field of the Invention
The present invention is related to a method and apparatus for preventing accidental pricks from needles of hypodermic syringes and for supporting hypodermic syringes.
2. Description of the Prior Art
Most hypodermic syringes now in use by medical personnel in hospitals and physician's offices are of a disposable type. Such syringes are typically manufactured entirely of plastic, except for the needle and in some cases the needle base. Such a hypodermic syringe includes a cylindrical barrel which narrows to a luer lock fitting at one end and has an opposite open end from which a pair of finger support flanges extend laterally outwardly in diametrical opposition to each other. A plastic plunger having a piston on its tip is inserted into the open end of the syringe barrel. A conventional hypodermic syringe also includes a metal needle element having an elongated, hollow needle with a somewhat larger cylindrical annular needle base with a radially outwardly directed lip at its open end. The lip of the needle base is coupled to the luer lock fitting of the barrel with a twisting or screwing action.
A conventional hypodermic syringe also includes a needle guard or cap in the form of a hollow, elongated plastic structure. The needle cap receives the syringe needle through an open, accessible end that fits snugly over the needle base in frictional engagement therewith. The opposite end of the needle cap is a closed or blind end.
To use a hypodermic syringe, the needle cap is removed and the distal tip of the needle is inserted into a liquid to be injected. The plunger is then retracted from the barrel, thus drawing liquid into the barrel, through the needle by means of suction. Filling of the syringe can either be performed locally in a hospital or in a physician's office. Often, however, the syringe barrel arrives at the medical facility pre-loaded with a liquid therein.
In either event, when the liquid is to be injected into a patient the distal tip of the needle is pressed into the skin of the patient and the plunger is depressed using the thumb of one hand with two fingers of the same hand bearing against the undersides of the laterally projecting finger support flanges. Once the liquid has been injected, the needle is withdrawn from the skin of the patient. If the entire contents of the syringe have been injected into the patient, the syringe must be discarded. Alternatively, in some cases several applications of a liquid in the syringe must be applied to different areas of the skin of the patient during the course of a surgery. In either event, the sharp needle, once having penetrated and then been withdrawn from the skin of the patent, represents a considerable hazard. Therefore, the needle is normally capped or sheathed.
The cap for a needle of a conventional medical syringe is an elongated, hollow sheath, closed at one end and having an open mouth at the opposite end. To replace the cap on the needle the physician or nurse must grasp the cap in one hand and the hypodermic syringe in the other and move the needle into the open mouth of the cap until the mouth is secured by friction about the base of the needle. However, the physician or nurse will occasionally misjudge the alignment between the needle and the cap and accidentally stick the fingers or thumb of the hand grasping the barrel-shaped cap with the needle. This can occur when the needle either passes longitudinally alongside the cap to prick the finger of the physician or nurse, or by an even smaller misalignment in which the needle enters the interior wall of the cap at an angle and is deflected laterally outwardly therethrough. In the latter instance the needle can pass outwardly entirely through the wall structure of the cap and prick the hand of the physician or nurse holding the cap.
Not only are needle pricks painful and distracting to the physician or nurse performing the surgery, but they can be extremely dangerous. A physician or nurse can contract hepatitis due to an accidental needle prick in capping a hypodermic syringe which has been withdrawn from the skin of a patient already infected with hepatitis. Likewise, other viral diseases can similarly be transmitted accidentally. The concern with respect to accidental needle pricks in the medical profession is now particularly acute due to the spreading prevalence of the deadly AIDS virus.
Several different approaches have been employed to attempt to eliminate the danger of accidental needle pricks following use of a hypodermic syringe. One approach is to construct the hypodermic syringe with a sleeve reciprocally mounted relative to the barrel of the syringe. After using the syringe the sleeve is pulled longitudinally along the barrel and over the needle until it provides a cylindrical annular guard disposed about the needle. Some typical reciprocal sliding needle sheaths or sleeves are disclosed in U.S. Pat. Nos. 4,747,837; 4,840,619; 4,968,304; and 4,723,943. However, the provision of a sliding sheath and the interlocking mechanisms associated therewith adds considerably to the complexity and expense of fabrication of the disposable hypodermic syringe product. Also, such systems require the physician or nurse utilizing the syringe to employ both hands in order to slide the sheath over the needle.
Another approach which has been employed to reduce the likelihood of needle pricks is to employ a large device that grips the needle cap while protecting the hand of the user. One such device is depicted in U.S. Pat. No. 4,955,865. This device is a hand held needle cad holder of rather intricate and expensive construction. This needle unsheathing and re-sheathing and handling apparatus is quite expensive, compared to the cost of disposable hypodermic syringes, and requires two hands for operation. A variation of this system is sold as a recapper stand by On-Guard Systems, Inc. located in Denver, Colo. This stand is provided with a base that rests upon a flat horizontal surface and has essentially the same operating mechanism as that described in U.S. Pat. No. 4,955,865. However, although this stand allows a needle to be recapped using one hand, it is quite expensive when considered in relation to the minimal expense of a conventional hypodermic syringe.